Transcriptional profile throughout the X-inactive specific transcript (XIST) locus in the placenta of cattle
X chromosome inactivation (XCI) compensates for the imbalance in gene expression between sexes. In mice, it is well established that the long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is essential for initiating XCI. The most well-known antisense transcript of the mouse XIST locus is TSIX, a negative modulator of XIST. However, in cattle, these events are not yet well established. In this study, we characterized the patterns of strand-specific transcription along the XIST locus in bovine fetal placenta, since understanding the regulation of gene expression in the placenta and of the transcripts involved in XCI in order to minimize embryonic and fetal losses due to the use of assisted reproduction techniques (ARTs) is key for livestock production. Sense transcription was detected throughout the XIST locus in male and female, and antisense transcription was detected in exon 1 of female fetal cotyledons. The sense transcripts may be lncRNA XIST, while the antisense transcript identified in exon 1 is not TSIX, but rather other uncharacterized RNAs. Moreover, our results show the relevance of taking into account the possibility of antisense expression for gene expression studies, especially in non-coding RNA or pseudogenes loci, where transcription from the two DNA strands is not rare. Taken together, the results show the importance of characterization as an aid to a better understanding of XCI in cattle, considering that epigenetic reprogramming can be impaired in cattle by the use of ARTs.